Writing instrument



FIG. 1 is a perspective view of a writing instrument;

FIG. 2 is an elevation view thereof, representing a front, rear, left, and/or right elevation view thereof;

FIG. 3 is a top plan view thereof; and,

FIG. 4 is a bottom plan view thereof.

The broken lines in the drawings illustrate portions of the writing instrument which form no part of the claimed design. 

CLAIM The ornamental design for the writing instrument, as shown and described. 